[Delivers #48917517] Fixed the issue for missing default regions in london

### Fixes
- https://www.pivotaltracker.com/story/show/48917517
- https://github.com/rackspace/openstack.net/issues/81

### Changes
- Added a check to the provider base to explicitly set the region to __LON__ when the following are all satisfied:
    - There is no region passed into the method
    - There is no default region retruned from the identity service
    - The identity is of type __RackspaceCloudIdentity__ and has the __CloudInstance__ = UK
- Removed the integration tests from the main .sln file, and moved them to their own .sln file *openstack.net_Integration_Tests.sln*
- Removed the documentation project from the main .sln file, and moved it to its own .sln file *openstack.net_Documentation.sln*